From: David Woodhouse <dwmw2@infradead.org>
To: Bjorn Helgaas <helgaas@kernel.org>, Paul Menzel <pmenzel@molgen.mpg.de>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: `pci_apply_final_quirks()` taking half a second
Date: Sat, 08 Apr 2017 19:00:19 +0200 [thread overview]
Message-ID: <1491670819.6021.33.camel@infradead.org> (raw)
In-Reply-To: <20170408154128.GA16832@bhelgaas-glaptop.roam.corp.google.com>
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On Sat, 2017-04-08 at 10:41 -0500, Bjorn Helgaas wrote:
>
> > Measuring where time is spent during boot with `systemd-bootchart`
> > on an Asus A780FullHD, it turns out that half a second is spent in
> > `pci_apply_final_quirks()`.
>
> I agree, that seems like a crazy amount of time.
>
> Can you figure out how to turn on pr_debug() (via the dynamic debug
> mess or whatever) and boot with "initcall_debug"? That should tell us
> how long each quirk took.
It could well be spending a fair amount of time just attempting to
match each device against the list. When I first implemented the table-
based quirks, back in the mists of time, there were relatively few.
Now I wonder if it's worth sorting the list by vendor ID or something,
at least for the common case of the quirks which match on
vendor/device.
I note it's also reading PCI_CACHE_LINE_SIZE From config space for each
device in pci_apply_final_quirks(). How long does that take?
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next prev parent reply other threads:[~2017-04-08 17:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-07 21:07 `pci_apply_final_quirks()` taking half a second Paul Menzel
2017-04-08 15:41 ` Bjorn Helgaas
2017-04-08 17:00 ` David Woodhouse [this message]
2017-04-08 19:06 ` Bjorn Helgaas
2017-05-03 18:42 ` Andy Shevchenko
2017-12-26 15:55 ` Paul Menzel
2017-12-28 21:27 ` Bjorn Helgaas
2017-12-29 16:14 ` Alan Stern
2017-12-31 7:18 ` Paul Menzel
2017-12-31 21:16 ` Alan Stern
2018-01-01 10:21 ` Paul Menzel
2018-01-01 15:47 ` Alan Stern
2018-06-24 16:49 ` `quirk_usb_handoff_ohci` takes over 73 ms (twice) on AMD system (was: `pci_apply_final_quirks()` taking half a second) Paul Menzel
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